Create a private value for the player which counts the jumps. Leave this value at default 0. Everytime the player jumps, add 1 to this value. (Jumps)Create another value which will be set to Random(5) + 1 on startup. (SoundTime)

Now if Jumps is equal to Soundtime => play SoundIf Jumps is equal to 5 => Set Jumps to 0 and Soundtime to Random(5) + 1